1. Field of the Invention
The present invention relates to a cassette for containing a magnetic tape cassette to be used preferably for a video tape cassette, and more particularly to such a cassette capable of preventing engagement members of a reel locking device from being deteriorated to make it possible to certainly lock reels, and also capable of decreasing the number of parts constituting the reel locking device.
2. Description of the Related Art
FIG. 1 illustrates an inside structure of a conventional cassette for containing a magnetic tape (hereinafter, referred to as "magnetic tape cassette). A video tape cassette 5 comprises a cassette half 51 (an upper cassette half is removed for clarity, and hence only a lower cassette half is illustrated in FIG. 1) in which a pair of reels 52 and 53 are disposed for rotation. Around each of the reels 52 and 53 is wound a magnetic tape 54. The magnetic tape 54 is guided by tape guides 55 and 56 disposed in the vicinity of a front (an upper side in FIG. 1) and at opposite sides of the cassette 5 so that the magnetic tape 54 passes along an opening 57 formed in the vicinity of the front of the cassette half 51. The reels 52 and 53 are formed with lower flanges 58, 59 which are formed at a whole perimeter thereof with teeth 60 and 61, respectively.
There is disposed a lock member 62 which is disposed in an almost triangular space located in the vicinity of a rear of the cassette 5 and between the pair of the reels 52 and 53, and which acts as a reel locking device for preventing the reels 52 and 53 from rotating in order not to loosen the wound magnetic tape 54 in transportation and handling thereof while the video tape cassette 5 is not being loaded in a video deck (not illustrated).
The conventional lock member 62 is formed with almost triangular shaped ribs 80 and 81 between a rear plate 63 of the cassette half 51 and the pair of reels 52, 53. The ribs 80 and 81 have straight portions 65 and 66 extending in a front-rear direction of the cassette half and parallel to each other, and an engagement member 67 is slidably interposed between the straight portions 65 and 66. A compressed spring 68 disposed between the rear plate 63 and the engagement member 67 exerts pushing force on the engagement member 67 towards the front of the cassette half. The engagement member 67 is formed at a bottom surface thereof with an opening 69 through which a lock-releasing pin of a video deck is to be inserted. The cassette half 51 is formed at a bottom surface 70 thereof with an opening (not illustrated) located in alignment with the opening 69 of the engagement member 67.
The engagement member 67 is suitably made of elastic resin, and has a rectangular-shaped slide body 71 having a relatively wide bottom surface area for stable slide movement, as illustrated in FIG. 2. The slide body 71 is integrally formed at a front end surface thereof with a pair of engagement claws 72 and 73 which are engagable to the teeth 60 and 61 formed with the reels 52 and 53, respectively.
The engagement claws 72 and 73 are designed to be relatively long and to have thin hinge portions 74 and 75, respectively, at the proximal ends of the engagement claws 72 and 73, that is, at joint portions connecting the engagement claws 72 and 73 to the slide body 71. Thus, the engagement claws 72 and 73 are able to elastically and transversely swing as shown with arrows A in FIG. 2. As illustrated in FIG. 2, a guide member such as pins 90 are disposed on the cassette half 51 in a projecting fashion. The pins 90 ensure that the engagement claws 72 and 73 open relative to each other to engage to the teeth 60 and 61 for locking the reels 52 and 53 as the slide body 71 makes slide movement towards the front of the cassette half, and that the engagement claws 72 and 73 close relative to each other or move towards each other to move away from the teeth 60 and 61 for releasing lock of the reels as the slide body 71 makes slide movement towards the rear of the cassette half. The magnetic tape cassette having the reel locking device as mentioned above is suggested, for instance, in Unexamined Japanese Patent Publication No. 7-14342.
On the other hand, there has been suggested another magnetic tape cassette 8 as illustrated in FIG. 3 in which engagement portions 200 and 201 are prepared separately from a slide body 202, and are secured to a cassette half 83 for rotation. The engagement portions 200 and 201 are maintained to be pushed towards the reels 85 and 86 by a spring 84. For instance, refer to Unexamined Japanese Patent Publication No. 6-44733.
When the video tape cassette 8 is not being loaded into a video deck, the slide body 202, which is designed to be slidable by a suitable guide member in a front-rear direction of the cassette, is pushed by a compressed spring 87 to the foremost movement location. In this stage, the engagement claws 88 and 89 are guided to insert into the adjacent teeth 95 and 96, respectively, so that the reels 85 and 86 are surely locked.
When the video tape cassette 8 is loaded into a video deck, the slide body 202 retreats with the result that engagement members 92 and 93 of the engagement portions 200 and 201 are pushed by the slide body 202 towards the rear of the cassette. Thus, the engagement portions 200 and 201 are made to rotate in clockwise and counterclockwise directions, respectively, and hence the engagement claws 88 and 89 are made to come out of engagement with the teeth 95 and 96, resulting in that lock of the reels 85 and 86 are released.
In the former video tape cassette 5, the engagement claws 72 and 73 are designed to be elongated and to have the hinge portions 74 and 75 by forming the proximal ends of the engagement claws 72 and 73 to be thin so that the engagement claws 72 and 73 of the engagement member 67 of the lock member 62 are transversely swingable. Thus, the hinges 74 and 75 are often fatigued when the video tape cassette 5 falls on a floor or by long term use, for instance, so that the engagement claws 72 and 73 would be broken at the hinge portions 74 and 75 or would be deformed plastically with the result of uncertain lock of the reels 52 and 53.
On the other hand, in the latter video tape cassette 8, the magnetic tape cassette has to have a greater number of parts since the engagement portions are formed separately from the slide body, and the spring 84 has to be prepared for urging the engagement portions 200 and 201 toward the reels. In addition, the video tape cassette 8 has much complexity in assembling thereof. In particular, each of parts has to be small in a small-sized magnetic tape cassette. Thus, if there are a great number of parts, the assembling of the cassette unpreferably takes too much time and labor. The above mentioned problem also arises in various types of magnetic tape cassettes as well as the video tape cassettes 5 and 8.